1. Field of the Invention
The present invention relates to an optical element, and more particularly to an optical element that utilizes electrodes to apply a voltage to change the slope of an interface between two liquids with different phases so that the light path of a light beam is changed.
2. Description of Related Art
Due to current demands for camera phones, a wave of upstream business opportunity for materials and device components of mobile phones is likely to appear. In particular, camera modules are going to be one of the most important developing items. According to a developing trend of the mobile phones, most of the mobile phones have a camera module with digital focusing function. Because mobile phones have to occupy a small volume, the digital focusing is a convenient selection. However, the digital focusing cannot completely satisfy the demands of consumers anymore. Yet, optical focusing module, when applied to a camera phone, has the setback of occupying a relatively large volume. As a result, the optical focusing module having a small volume is now one of the goals in research. The French Company Varioptic and the Dutch Company Philip have separately developed small volume liquid-control automatic optical focusing modules. The French Company Varioptic has authorized the Korean Company Samsung to apply the technique to the camera module of the camera phone. However, the liquid lens technique is mainly applied to optical focusing. In fact, the only function of the liquid lens is to change the focus and nothing else.
For example, in U.S. Pat. No. 6,369,954 with the title ‘LENS WITH VARIABLE FOCUS’, a variable zoom lens is proposed, as shown in FIG. 1. The variable zoom lens includes a chamber 12 filled with a first liquid 13 and a second liquid 11 in the form of a drop disposed on a connecting area 15 of an inner surface of the chamber 12. The inner surface of the chamber 12 and the area surrounding the connecting area 15 have specially treated surfaces 14 for maintaining the drop configuration of the second liquid 11. The liquids 11 and 13 are transparent and immiscible and have different optical indexes. On the outer surface of the chamber 12, electrodes 16 are laid around the connecting area 15 and another electrode 17 is electrically connected to the first liquid 13. When a voltage is applied to the electrodes 16 and 17, a corresponding electric field is produced so that the shape of the liquid drop 11 is changed. Thus, by using two layers of the liquids 11 and 13 with two different phases and applying a voltage to change the interface curvature (from curvature A to curvature B in FIG. 1), the focus of an incident light beam is changed. The mechanism is mainly applied to an optical lens. In this patent, there is a change in the curvature of the interface between the two liquids after a voltage is applied. Hence, a change of focus of an incident light beam is facilitated. However, this structure only changes the focus points and provides no other functions.
In U.S. Pat. No. 6,603,444 with the title ‘DISPLAY ELEMENT AND DISPLAY DEVICE HAVING IT’, a type of display element to be used in a display device is proposed. The display elements are assembled as pixels of the display device. As shown in FIGS. 2A and 2B, the display elements are enclosed within the first substrate 101 and the second substrate 102. An active element array substrate 103 disposed therebetween is regarded as a first electrode. Furthermore, the display elements further include an insulating layer 104, a surface treatment layer 105, a first liquid 106, an electroconductive electrolyte solution 107, a second liquid, an inverting electrode 108 and a mask 109. This patent uses different voltages to change the curvature of the liquid interface so that light beams are allowed to penetrate through the focusing points. Other than the focusing points, the light beam can be blocked. Therefore, by using a suitable voltage to control the focusing points, the penetration of an incident light beam can be controlled to form bright and dark dots in the display device. For example, when 0(V) volt is applied as shown in FIG. 2A, dark dots 120 appears on the display device. On the other hand, when V0 (V) volt is applied as shown in FIG. 2B, bright dots 122 appears on the display device. However, the main function in the present case is to change the focus in order to control brightness and darkness while other functions are not provided. In other words, it is purely an application of curvature modification to change the focusing point of an incident light beam.